Various process gases may be used in the manufacturing and processing of micro-electronics. In addition, a variety of chemicals may be used in other environments demanding high purity gases, e.g., critical processes, including without limitation microelectronics applications, wafer cleaning, wafer bonding, photolithography mask cleaning, atomic layer deposition, chemical vapor deposition, flat panel displays, disinfection of surfaces contaminated with bacteria, viruses and other biological agents, industrial parts cleaning, pharmaceutical manufacturing, production of nano-materials, power generation and control devices, fuel cells, power transmission devices, and other applications in which process control and purity are critical considerations. In those processes, it is necessary to deliver specific amounts of certain process gases under controlled operating conditions, e.g., temperature, pressure, and flow rate.
For a variety of reasons, gas phase delivery of process chemicals is preferred to liquid phase delivery. For applications requiring low mass flow for process chemicals, liquid delivery of process chemicals is not accurate or clean enough. Gaseous delivery would be desired from a standpoint of ease of delivery, accuracy and purity. One approach is to vaporize the process chemical component directly at or near the point of use. Vaporizing liquids provides a process that leaves heavy contaminants behind, thus purifying the process chemical. Gas flow devices are better attuned to precise control than liquid delivery devices. Additionally, micro-electronics applications and other critical processes typically have extensive gas handling systems that make gaseous delivery considerably easier than liquid delivery. However, for safety, handling, stability, and/or purity reasons, many process gases are not amenable to direct vaporization.
There are numerous process gases used in micro-electronics applications and other critical processes. For example, ozone is a gas that is typically used to clean the surface of semiconductors (e.g., photoresist stripping) and as an oxidizing agent (e.g., forming oxide or hydroxide layers). One advantage of using ozone gas in micro-electronics applications and other critical processes, as opposed to prior liquid-based approaches, is that gases are able to access high aspect ratio features on a surface. For example, according to the International Technology Roadmap for Semiconductors (ITRS), current semiconductor processes should be compatible with a half-pitch as small as 14-16 nm. The next technology node for semiconductors is expected to have a half-pitch of 10 nm, and the ITRS calls for <10 nm half-pitch in the near future. At these dimensions, liquid-based chemical processing is not feasible, because the surface tension of the process liquid prevents it from accessing the bottom of deep holes or channels and the corners of high aspect ratio features.
The steps for producing patterned structures on next generation semiconductor devices are requiring lower thermal budgets due to high aspect ratios and heat sensitive materials. To achieve reactions at lower temperatures and to attain full coverage, highly reactive reducing and oxidative liquid chemistries need to be delivered in the vapor phase. Traditional vapor phase delivery methods, e.g., bubblers, are incompatible or ineffective with these new chemistries. For example, bubblers and other analogous devices cannot be heated above about 40° C. with volatile and reactive chemistries, such as hydrogen peroxide or hydrazine containing solutions, which limits the ability to provide higher concentrations of reactive chemistries to critical process applications. In addition, using bubblers and other analogous devices to deliver volatile and reactive chemistries can result in the concentration of the reactive chemicals in the liquid and gas phase of the device increasing during operation of the device. Another shortcoming of many prior devices, systems, and methods is that they cannot safely and/or consistently deliver a high concentration gas stream containing a volatile and reactive chemical, or they cannot sustain the delivery of a high concentration gas stream containing a volatile and reactive chemical over a long period of time, which is often required of in a critical process environment, such as various semiconductor manufacturing processes and other processes. When critical process applications require a higher concentration of a volatile and reactive chemical than can be provided directly from prior devices, systems, and methods, a concentrator or similar device may be used to trap and concentrate the volatile and reactive chemical. But concentrators and similar devices increase the complexity and decrease the efficiency of such devices, systems, and methods, while also presenting safety concerns regarding potential dangerous concentrations of volatile and reactive process gases.
Disclosed herein are devices, systems, and methods for delivering high purity chemicals in the vapor phase to critical processes, e.g., semiconductor, medical, and pharmaceutical applications, that overcome the limitations of prior devices, systems, and methods. The devices, systems, and methods disclosed herein enable consistent delivery of volatile and reactive process gases, such as hydrogen peroxide or hydrazine, over a wide range of concentrations, including relatively high concentrations that would not be possible or safe with prior devices, systems, and methods.